Waterproof fibrous product



Patented Oct. 25, 1932 UNITED STATES PATENT OFFICE HAROLD L. LEVIN, OF NUTLEY, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE FLIN'IKOTE CORPORATION, OF BOSTON, MASSACHUSETTS, A CORPORATION OF IVIASSAGHU SETTS 1N0 Drawing.

This is a continuation in part of my former application, Serial Number 231,790, filed November 7th, 1927, now Patent No. 1,785,357, dated December 16, 1930.

This invention relates to waterproof fibrous products and more particularly to waterproof sheet material and a process of producing the same.

Among the objects of the invention, I aim to provide sheet waterproof material composed of a minor proportion of fibre, and a major proportion of filler materials adapted to impart various desirable characteristics to the sheet, as will be hereinafter pointed out.

Another object of the invention is to provide a sheet of this character which, despite its low fibre content, will nevertheless possess sufficient structural strength to permit its ready handling as it is taken in the form of a wet web from the forming-mechanism, and to Withstand when dry and finished, the

' ordinary wear to which it is subjected in use.

Another object is to provide a fibrous prodnot of this character having thermo-plastic properties, and which because of its low content of fibre, lends itself very readily to processes of thermo-moulding for the production of sharp cameo or intaglio eflects, without tearing, breaking, or otherwise injuring the.

1 Still another object is to provide a fibrous sheet of the character described, in which the fibrous content thereof is so low, and so related to the other constituents of the sheet, that swelling and shrinking, due to absorption and elimination of water or moisture, is

. small proportion of fibrous constituents.

- In carrying out the invention I may em- WATERPROOF IEIBROUS PRODUCT Application filed November 22, 1930. Serial No. 497,611.

ploy fibres of various descriptions, such as wood pulp, either chemical or mechanically ground, animal fibre, as for example hair or vegetable tan or chrome tan leather, or I may employ mineral fibres such as asbestos, or the like. In certain instances the fibrous stock may be composed of a suitable mixture of the fibres above indicated, it being obvious that in selecting the fibres to be used one is to be guided by the requirements for tensile strength desired in the sheet, within the scope of the invention.

In carrying out the invention the wood pulp .or other fibrous stock is placed in a heater engine, together with sufficient water to permit ready circulation during the heating operation.

To the fibrous stock in the beater engine is then added the waterproofing material. The

latter is intended, not only to afford waterproofing properties in the product, but is adapted also to serve in binding the fibers, strengthen the sheet and provide also a substantial degree of thermo-plasticity in the product. The strengthening of the sheet is thus accomplished both in its dry and finished state and in its wet state upon formation, so that the "wet sheet,having the low fibre contentcontemplated by the present invention,

is not so tender and devoid of tensile strength as to disintegrate when being removed as a wet web from the forming instrumentality.

As the waterproofing material, I may use any suitable bituminous substance such as asphalts, pitches, tars, resins or resinous materials, or the like, and I prefer to incorporate the same with the fibrous stock in the form of a dispersion in water. The dispersion should be any suitable type which is not broken down by flocculents or precipitants, and which is stable to the pressures and other influences to which the sheet may be subjected during its formation, so that no gumming of the forming inst-rumentalities will ensue. Preferably the dispersion is one produced in accordance with a method described in Patent No. 1,615,- 303 issued to Lester Kirschbraun dated J anuary 25, 1927. Such dispersion may be of a Mexican asphalt of to 200 F. melt point, the dispersion whereof has been attained as described in said patent with any one or a mixture of dispersive media enumerated therein, or with any other suitable dispersing agent. The dispersion may be composed of, say, 50 parts of the asphalt, 10 parts of the dispersing agent and parts water.

Instead of bitumens as heretofore enumerated, I may in certain instances, employ other hydrocarbons such as rubber, the latter being preferably made into an aqueous dispersion as set forth in Patent No. 1,498,387 issued to Lester Kirschbraun on June 17, 1924.

I may also, in certain desirable instances, utilize as the waterproofing material a combination of rubber and bitumen in aqueous dispersed form, produced as for example by the method disclosed in my prior application Serial No. 100,714 filed April 8, 1926.

The dispersion, by whatever method it is prepared, and diluted, if necessary, with water, is then mixed with the stock in' the beater engine and thoroughly disseminated through the same by the action of the beater roll. The quantity of dispersion mixed with the fibrous stock will depend largely upon 9 the properties desired in the final product to be produced. Thus, where asphalt is used, and the product desired is one which is substantially rigid, waterproof, and thermoplastic, I may add theasphalt dispersion in amounts'sufiicient to produce a sheet in which the fibrous content is substantially equal to the asphaltic content thereof. Thus, where the sheet is composed of about 30% fibres, the asphalt may constitute 28% to 33% of the sheet, the balance being made up of thefiller.

The filler may be any suitable material adapted to provide the necessary weighting and bulking of the sheet and may include rosin powder, cork, sawdust, rubber dust, or similar material, as well as insoluble mineral pigments to impart the desired color to the product. If desired, vulcanizing agents such aspowdered sulphur or'the like, may be added to vulcanize and render infusible the bitumen or rubber hydrocarbon used. The filler should preferably be comminuted sufliciently fine to pass a sieve of20 mesh. While, as

' fibres to prevent swelling and shrinking acabove stated, the filler functions to bulk and weight the sheet, there is an additional advantage inherent in the present invention, and that is, that with a sheet whose fibrous constituents comprise only 30% to 35% thereof, the large amount of solid amorphous filler and asphalt acts as a separator between the tion from taking place and compounding itself to such'an extent as to cause warping or similar distortion of the sheet.

The filler is added to the fibrous stock and the dispersion in the beater and thoroughly admixed therewith, whereupon any soluble reacting salts such as soda 'ash, sodium silicate, and alum, may be added to mass in the beater, whereby to forin a precipitate which is adapted to cause the dispersed asphalt particles to be fixed on the fibres. Preferably, the alum is employed in such quantities as to adjust the hydrogen ion concentration of the stock to the iso-electric point of aluminum hydroxide, say of pH 4.5 to 5.5.

In a typical furnish which has been used in carrying out the invention, the fibres were composed of 360 parts of mixed paper. and parts of soft leather. The dispersion, on the dry basis, comprised about 500 parts of the furnish, and the filler was composed of about parts of sawdust, 200 parts asbestine, and 200 parts of yellow clay, and a small quantity, say, 10 to 15 parts of bone black.

In order to fix substantially all the asphalt in such a furnish upon the fibres thereof, about 15 .parts of soda ash, 20 parts of sodium silicate, and 60 parts of alum are required.

The illustration here given will result in the. production of a black waterproof fibre board. Where colors are desired, the composition of the filler may be modified to produce the desired efi'ects. Thus, where a red board is desired, having substantially the fibrous and asphaltic content as given in the first example, the filler may be coinposed of 85 parts sawdust, 15 to 20 parts asbestos, 40 parts asbestine, and 400 parts red oxide.

In another run, where an asbestos product was desired, the stock was composed of 20 to 25 parts of low grade asbestos fibre, 70 parts of asphalt dispersion containing about 50% asphalt, and 40 to 45 parts of mineral fines in the form of an impalpable asbestos dust. To this stock was added the necessary amount of precipitating agents such as sodium silicate and alum, as above described.

It should be obvious however, that the above figures are given merely by way of example, and that wide variations may be made therein, within the scope of the invention.

As soon as the precipitating agents have been incorporated, the stock is transferred to a wet or cylinder machine for formation into a web, which is then carried by blankets from the forming cylinder to the make-up roll where a sheet of desired caliper may be built up. y

If desired, mottled effects may be obtained by using stocks of contrasting colors.

For non-skid properties, any suitable powder such as rubber-dust or the like may be dusted onto the web after formation and various decorative or ornamental effects. In-

certain instances, as where a rigid board is desired, Portland cement, plaster of Paris, or other hydraulic cementitious material may be dusted onto the wet web at this stage, so

that the cement combined with the successive convolutions as built up on the make-up roll, will be hydrated and set by the water present in the wet sheet. a

When a. web of desired caliper has been built-up, it is then stripped from the make-up roll and dried to remove the water.

The sheet may then be passed through hot calender rolls, or heated and passed through cold calender rolls, or otherwise treated so as to heat the same to a temperature sufficient to cause the particles of waterproofing material to coalesce and fuse on the fibres, and form a hard, rigid and thermoplastic boardlike structure. Where vulcan'izing agents have been included, the heat and pressure will also serve to vulcanize the hydrocarbon in situ, so as to render thesame infusible.

If desired, the sheet may be subjected to the action of a hot press-plate to cause the necessary fluxing and obtain a smooth appearance.

By virtue of the thermoplastic properties of the sheet as thus produced, it may be moulded in various shapes under heat and pressure, or embossed or impressed with designs either simultaneously with, or subse quent to the pressing action, and the outlines of such designs may be made as sharp and distinct as desired, and by reason of the low fibre content of the sheet, the embossment or indentation may be carried on effectively without giving rise to cracks in the sheet as by the breaking of the fibres thereof.

The board may if desired, be cut into various shapes and sizes, either simultaneously with or after the pressing action, and employed for such purposes as wall panels, ceiling panels, gaskets, friction wear surfaces,

commercial signs, and the like.

Another particularly novel and advantageous feature of my invention resides in the fact that the wet fibrous sheet, after being removed from the make-up roll, may, while in its wet state, be shaped as by'stamping, into articles of various shapes and designs. In this way, any waste produced during the moulding or shaping process, being free of coalesced asphalt, may be recovered and returned to the heater for re-use. Furthermore, due to the mechanical stresses imposed on the fiber in making a deep draw" in the embossing and thermo-1noulding of thermoplastic board, it is not possible to exceed a draw of approximately two inches with a heard one quarter inch thick without so disturbing the fibers that the mechanical strength of the board is impaired to a substantial extent. By moulding or shaping the board in its wet state, I find that it becomes possible to produce articles of irregular or hollow shape, the

configuration of which would not lend itself for practical thermo-moulding operations. Thus the wet board maybe shaped prior to drying to an extent sufficient to obtain an approximation of the shape desired in the finished article. The article as thus shaped in its wet state, may then be dried and being removed from the make-up roll, may

be pressed upon a suitable screen form which will cause the board to take the shape desired, and preferably, the thus shaped board is permitted to dry on the screen form. The dried and perhaps partially shaped article, may then be pressed between heated male and female dies and thus brought to final shape, and if desired, may at the same time be formed with any desired surface embossments or other ornamentation, all without distortion or stressing of the fibers. It will be understood by those skilled in the art that by reason of the fact that the major extent of the forming or moulding is accomplished in the wet state, leaving a comparatively small amount of formation work to be done upon the dried structure, the aforedescrib'ed fea ture and advantage may be availed of with any suitable stock containing say from to fiber and 20 to 60% of dispersion.

It will be understood, of course, that the article fabricated in the manner here described, will have theasphalt fused and coalesced therethrough under the action of the heat and pressure which obtains during r the final pressing or thermo-moulding operation.

I claim as my invention:

1. The method of making waterproof fibrous objects which comprises admixing fibrous stock and an aqueous dispersion of thermoplastic waterproofing material, forming said mixture into a wet board on a paper making machine, forming said board toapproximate shapev while in its wet state, drying the board in said shape and subjecting the dried board to heat and pressure.

2. The method of making waterproof fibrous objects which comprises admixing fi-. brous stock and an aqueous dispersion of thermoplastic waterproofing material, forming said mixture into a wet board on a paper making machine, pressing the wet board to approximate desired shape on a form, drying the thus shaped board and subjecting the dried board to thermo-moulding to bring it to final shape and surface contour.

3. The method of making waterproof fibrous objects which comprises running off a mixture of fibrous stock and thermoplastic waterproof material on a paper machine for the formation thereofinto felted wet board, bringing said board substantially to the shape of the desired article while 1n its wet shaped article, and'subjecting the dried arstate, drying the shaped article, and subjecting the dried article to heat and pressure.

4. The method of making waterproof fibrous objects which comprises running off a mixture of fibrous stock and thermoplastic Waterproof material on a paper machine for the formation thereof into felted wet board, bringing said board to approximately the shape of the desired article by pressing it in its wet state on a form, drying the thus ticle to heat and pressure.

5. A method of making waterproof fibrous objects which comprises admixin fibrous stock and an aqueous dispersion o thermoplasticwaterproofing material, forming said mixture into a sheet on a paper making machine, the character and relative proportions of the fibre and the thermoplastic waterproofing material being such as to render the sheet thermoplastic when dry to permitv it to withstand embossing action without tearing, breaking or otherwise injuring the unitary nature of the board, shaping the sheet in its wet state to substantially the desired form, subjecting the shaped material to drying action and thermo-moulding the dried and shaped article.

6. The method of making waterproof fibrous objects which comprises admixing fi-' brous stock, filler, and an aqueous dispersion of thermoplastic waterproofing material, forming said mixture into a'wet boardon a paper making machine, pressing the wet board to approximate desired shape on a form, drying the thus shaped board and subjectingthe dried boardto thermo-moulding to bring it to final shape and surface contour.

In testimony whereof I aifix my signature HAROLD L. LEVIN. 

